As background, persons with diabetes suffer from either Type I or Type II diabetes in which the glucose level in the blood is not properly regulated by the body. As a consequence, many persons with diabetes often carry specialized electronic monitors, called blood glucose (bG) monitors, to periodically measure their glucose level and take appropriate action, such as administering insulin. Blood glucose monitors commonly comprise a base unit that houses control and test electronics required to test the glucose level in a sample of blood. Typical bG monitors may also have a measurement strip receptacle that accepts a disposable measurement strip. One end of the strip is inserted into the measurement strip receptacle while an exposed area contains a reaction site in which the user deposits a drop of blood, which is often obtained by pricking the skin with a lancet. Conductors run from the reaction site, which comprises various reagent chemicals, to the end inserted into base unit, thereby electrically coupling the reaction site to the control and test electronics. For blood glucose measurement results to be valid, the temperature at the reaction site must be within established lower and upper bounds. Therefore, an accurate temperature reading at the reaction site is desired to necessarily validate a blood glucose measurement. Due to the fact that all but the base of the bG test strip is exposed to ambient air, the reaction site temperature closely follows the ambient air temperature.
In addition to the bG monitor, persons with diabetes may also carry a portable electronic device, such as a cellular phone, smart phone, music player, personal digital assistant (PDA), or other similar devices. In order to reduce the number of electronic devices carried by persons with diabetes, there is a desire for integrating bG measuring functionality into another portable electronic device. For example, a bG monitor may be integrated into a cellular phone so that a diabetic only has to carry such a single, multi-functional device.
However, many portable devices generate significant internal heat resulting from active and passive components within the device, such as power supplies, resistors, integrated circuits, microcontrollers and the like. For example, the core temperature of a cellular phone can rise over 20 degrees Celsius above the ambient temperature during continuous use over a period of twenty minutes. Blood glucose monitors commonly rely on an internal temperature sensor to determine the temperature at the reaction site. Difficulties arise when the temperature reading provided by the internal temperature sensor changes not due to changes in the ambient air, but rather due to the internal heating of electronic components inside the device. Furthermore, the internal heat generation may vary depending on how the portable electronic device is being used. Because the internal temperature of such portable devices fluctuates greatly depending on device usage (e.g., cell phone talk times) and therefore influences the internal temperature, an internal temperature sensor maintained within the device is not capable of obtaining an accurate reaction site temperature to validate the blood glucose measurement.
Accordingly, a need exists for alternative temperature estimation methods and blood glucose measuring devices incorporating the same.